Japan experienced an early summer heatwave on Sunday, May 10, 2026, as many regions recorded temperatures of 25 degrees Celsius or higher [1].
The sudden spike in temperature coincides with Mother's Day, drawing large crowds into city centers and outdoor festivities across the archipelago. This early arrival of summer weather suggests a potentially intense season ahead for the region.
In Tokyo, the highest temperature reached 24.8 degrees Celsius [1]. Nationwide, 139 locations recorded summer-day temperatures, defined as 25 degrees Celsius or more [1]. The warmth prompted many residents and visitors to spend the holiday outdoors.
In Hokkaido's Fukushima town, the warm weather coincided with a women-only sumo tournament. The event was organized to thank the women of the town for their support while the men were away at sea [1].
Some outdoor vendors struggled with the combined heat of the sun and their equipment. One grill operator said the perceived temperature at the cooking area was over 40 degrees Celsius [1]. The operator said the experience of working the grill was "hell" because the demand for food was so high that they could not keep up with the grilling [1].
Visitors in the city expressed surprise at the timing of the heat. One visitor said it already feels like summer and noted that a period of extreme heat likely awaits the country this year [1].
“139 locations recorded summer-day temperatures”
The occurrence of summer-day temperatures in over 100 locations as early as May indicates a shift in seasonal norms for Japan. When perceived temperatures at outdoor events exceed 40 degrees Celsius, it raises concerns regarding heat exhaustion for both workers and tourists, potentially signaling a trend toward more aggressive early-season heatwaves.
